Apparatus for the pneumatic separation of materials comprising elements of different specific weights, such as raw coal



Aug. 27, 1935. F. J. MEUNIER F 2,012,633

-APPARATUS FOR THE PNEUMATIC SEPARATION OF MATERIALS COMPRISING ELEMENTSOF DIFFERENT SPECIFIC WEIGHTS, SUCH ,AS RAW COAL Filed Nov. 22, 19252k 3Sheets-Sheet l F. J. Meunier* F. J. 'MEUNIER Aug. 27, 1935.

APPARATUS FOR THE'PNEUMATIC SEPARATION OF MATERIALS COMPRISING ELEMENTSOF DIFFERENT SPECIFIC WEIGHTS, YSUCH AS RAW COAL Filed Nov. 22, 1932 3Sheets-Sheet 2 Aug. 27, 1935. F, J MEUNlER 2,012,633

APPARATUS -FoR THE PNEUMATIC SEPARATION OF MATERIALS GOMPRISING ELEMENTS0F DIFFERENT SPECIFIC WEIGHTS, SUCH AS RAW COAL l iFiled. Nov. 22, 19323 Shee'os--SheeiI 3 Patented Aug. 27, 1935 'UNITED STATES APPARATUS FORTHE PNEUMATIC 0F MATERIALS COMPRISING ARATION SEP- ELEMENTS 0F DIFFERENTSPECIFIC WEIGHTS, SUCH AS RAW COAL Flicien Joseph Meunier,Neuilly-Sur-Seine,

' France Application November 22, 1932, Serial No..643,926 In FranceDecember 2, 1931 2 Claims. (Cl. 209-466) This invention has for itsobject improvements in apparatuses for the pneumatic separation ofmaterials comprising elements of different speciiic weights, such as rawcoal. The invention relates chiefly to apparatuses of this class whichcomprise one or more sloping surfaces or tables over which the materialto be separated is caused to travel and which are provided withapertures through which air under pressure is forced up- Wardly tostratify the bed of material.

The primary object of my invention is to improve the efficiency of theapparatuses of the general type above set forth, i. e. to increase theweight of material per unit of area of the perforated table which can betreated in a given lapse of time, thus reducing the length and bulk ofthe apparatus as compared with the heretofore known apparatuses of thesame class. Another object is to improve the dry separation process bypneumatic way so as to provide for a. proper adjustment, at each pointof the bed of material of the air draft with respect to the state of thebed at this point and for this purpose to provide for a separate andaccurate control of the air draft at various points of the bed ofmaterial so as to suit every working condition which may occur inpractice. A further object is t-o design an apparatus for carrying outsuch an improved process and more particularly to devise means wherebylthe air draft through the bed of material will be divided in a pluralityof separate air streams, the pressure of each of which is separatelyadjustable at will. A still further object of my invention is to provideimproved means for separating minerals of different specic gravities,after they have been arranged in layers upon the perforated table,without disturbing the general state of stratification of the materialbed.

With these and other objects in view as will appear hereinafter, myinvention resides in the novel combination of steps and in the novelarrangement of parts and provision of means as will be set forthhereinafter and more fully pointed out in the claims.

Various embodiments of my invention are illustrated by way of exampleonly in the annexed drawings in which:

Fig. 1 is a vertical longitudinal cross-section through an embodiment ofthe invention.

Fig. 2 is a .corresponding plan view.

Figs. 3 and 4 are transversal cross-sections taken along lines 3-3 and 44 of Fig. 1.

Fig. 5 is a detail longitudinal cross-sectional view according to line5-*5 of Fig. 2 and at a larger scale, of the schist removal device.

Fig, 6 is a corresponding sectional view taken along line 6 6 on Fig.q2of the pure coal removal device.

Fig. 7 is a part plan view of a modified em bodiment and Fig. 8 isavertical longitudinal section of another and still further improvedembodiment.

The apparatus illustrated comprises in a known manner a table I thebottom I2 of which is provided with apertures distributed over its wholeor substantially its whole area, means for forcing air upwardly throughsaid table I, and means for causing the bed of material formed onto saidtable to travel along thelatter. In the various embodiments illustratedsaid latter means consistin a slight longitudinal slope given to thetable and in a mechanism adapted to impart a reciprocating rectilinear4motion to the table as for instance an eccentric 9 keyed on a drivingshaft and connected through the eccentric rod l to the table I withinterposition of buffers 8; the

eccentricity is preferably adjustable, whereby al.-

lowing to vary the stroke of the perforated table. The means for forcingair through the table I consist preferably of a fan 5 the outlet ofwhich is connected to a stationary and air-tight casing 4 providedbeneath the table I and over its whole length. Said casing 4 serves as asupport for the table I .which rests thereon through the medium of ballbearings 2 provided with dampers 3. The ball bearings are preferablyadjustable in height whereby-the slope of the table can be varied.Flexible joints 6 connect the lower edge of the shaking-table with theupper edge of the aircasing so as to allow the reciprocating motion ofthe table over the air-casing while ensuring a hermetically air-tightconnection between these two parts.

The apparatus further comprises means Whereby at least a part of theundermost layer of the bed of material can be removed at predeterminedpoints of the path of the latter. In the embodiments shown in Figs. l, 2and 8 the apparatus is provided for this purpose with two suchremovalsections I3 extending Iacross the whole width of the table which isthu'sfgdivided into three concentrating sections II bt it couldobviously be provided with less or more removal sections.

The bottom ofthe table in these transverse re-l moval sections I3 ismade of solid iron-sheet and is preferably more inclined than theapertured bottom of the concentrating sections. Said solid iron sheet isapertured in a convenient manner to enable the heavier pieces whichconstitute the undermost layer of the bed to fall through the table intochannel means I4 provided below and a proper device enables to controlthis outflow of the heavier particles. The arrangement is preferably`asfollows (Fig. Each solid iron sheet I3 is provided with a continuoustransverse slot under and along which extends a shutter 22 manuallyadjustable by rotationv about its axis having a part in the shape of acylindrical surface coaxial with the pivoting axis and adapted to engageboth edges of the slot; thus, by rotating the shaft 22 I will vary thewidth of the slot and hence the discharge of the heavier pieces of thematerial subjected to treatment without disturbing the state ofstratification of the bed since the deflection of the Apath of thelatter around the shutter is quite progressive.

In order to provide for a more accurate separation of the heavierparticles from the bed I prefer to provide the perforated table on atleast part of the length of each concentrating sections or of some ofthem, and adjacent the following removal section, with a plurality oflongitudinal channels, open at their upper part and tapering in thedirection-of ,travel of the material, the height of said channels beingless than the thickness of the material bed. In both embodimentsillustrated said channels are defined by small angle bars 20 securedontothe perforated bottom I2 of the table in the-second half of eachconcentrating section. In the present instance there are in each sectionthree sets of two such bars 20 each, each set forminga kind of wedge andthe apex of the three wedges being situated ,on a common lineperpendicular to the longitudinal axis of the table. Theangle bars 20project from the bottom.l2 of a quantity far less than the height of thetable sides, in such a manner as not 'to substantially project above thelayer comprising the heavier particles already stratified. In this casethe discharge of the latter takes place through a plurality of dischargeopenings provided in the bottom of the table and in length- Wiseregister with said channels. However I still prefer to use as shutter 22a rotatable shaft having a single recess of a length substantially equalto the width of the table and to divide the slot in the table by pronglike extensions of the table bottom into as many separate openings asthere are channels for the heavier particles.

My improved apparatus is further provided with means for the removal ofthe uppermost layer of the material bed at intermediate points of thelength of the table. Such means is preferably located in the vicinity ofthe removal means for the undermost layer and consists for instance in ascraper 25 which can be adjusted at will to vary the thickness `of theremoved layer; this can be obtained in a. proper manner by pivotallymounting the scraper 25 and operatively connecting it to a controldeviceincluding a screw and nut contrivance and a handle wheel 26 asillustrated in Fig. 6. In the embodiment illustrated the scraping means25 does not extend over the whole table width but is' subdivided in aplurality of separate and separately adjustable Scrapers 25 locatedsubstantially in the same transverse removal section I3 as the removingmeans for the undermost layer but only in lengthwise register with theseparts of the table which are comprised between the sides of each of theaforesaid deflecting wedges. With such an arrangement the thickness ofthe material bed on the table progressively decreases from one sectionof the table Ato the next one as weli as the differences between thespecific weights of the various particles in the bed since the heavierand the lighter one are removed at various points of the table. As thethickness of the bed might become too small on the end concentratingsection I prefer to give to this section a progressively decreasingwidth and with a view to enable the apparatus to be used for thetreatment of materials having a small or large percentage of tailings Iprefer also to provide my apparatus with means whereby the useful widthof the end concentrating section and hence the thickness of the bed canbe adjusted at will. To this end I provide the end section with two sideangle bars 32 adapted to be swung apart or towards each other overthebottom of the table by means of a control device including a handlewheel 34 adapted to turn a screw 33 with two opposite pitchesrespectively in mesh with nuts secured to the side angle bars 32.

The discharge means at the end of the table includes a shutter or shaft21 similar tothe shutters 22 above described and a second similarshutter 28 located beyond the shaft 21, whereby the material can beclassified in three different categories, the shafts 21 and 28 servingrespectively to control the discharge ofthe undermost and intermediatelayers which fall into channels 29 and 30 while the uppermost layerwhich proceeds onover the shutter 28 is removed through the channel 3|.

In the modified embodimentlillustrated in Fig. 7, I use a kind of wedge36 axially movable and slidable on the table to adjust the width of theend concentrating section and I move said wedge by means of a controlcontrivance including a screw and a handle wheel.31.

It is to be noted thatby adjusting either the angle bars 32 or the wedge36 I vary the length of the discharge openings controlled by theshutters 21 and 28. 1

The operation of my improved apparatus is as follows:

The raw material, previously sifted into different categories which`have been stored separately in hoppers 35 feeding different apparatusesis distributed evenly by a feeding device 36 ontol the shaking table thefirst section I D of which acts as a sieve and serves for removingthrough a channel 31, the non-classified material resulting from theimperfect preliminary sifting together with all the dust due to thebreaking up of the material during its handling and storing.

The non-classified material and the dust are returned to the flrstsifting apparatuses and when they pass out of these they take againvtheir place in the corresponding categories.

In case of fine moist coal, an inlet 38 of forced air allows thecleaning of the sheet iron perforated with small holes; in this case,the feed is held up an instant through controlof a damper 39.

The material travels then along the table as usual in the apparatuses ofthis class and arrives on the first concentrating section II; the airdraft through the table in said section being properly adjusted a rstpneumatic stratification takes place in the first part of this firstconcentrating section. On arriving adjacent the defleeting surfaces 20,the undermost layer enters channels ows through a bed portion of lessthickber ma, 40h, 40C forms a second expanding chamness and deprivedfrom its undermost layer so that it acts now on mixed material and purecoal only. The separation is thus furthered in those regions andthe-uppermost layer removed by the scrapers 25- contains coal particlesin a quite pure state. The material proceeds yet onto the nextconcentrating table section where the same process takes place again.

As the thickness of the bed decreases progressively from one section tothe next one, as well as the differences between the specific weights ofthe various particles, it is a primary matter that the air pressureacting in each concentrating section can be accurately adjusted.

f yFurther it is known that the air-pressure must become greater as theheavier particles are settling on the bottom of the table. It is hencehighly desirable to have means whereby the air pressure can be adjustedto suit these various working conditions and, moreover during theworking of the apparatus'as the aforesaid working conditions are notpermanent ones but vary continuously with the state of the material, inparticular with its higher or lower grade of purity. My improved processof pneumatic separation contemplates therefore to use various airpressures in the various sections of the bed where concentration isproceededjwith, said pressures decreasing from one section to the otherin accordance with the direction of travel of the bed. and also variouspressures in one and the same section, said pressures increasing in theaforesaid direction. yThese pressures are preferably so graduated thatthe minimal pressure in a section is less than the minimal pressure inthe preceding section and .greater than the minimal pressure in thefollowing section. Still further my process contemplates varying at willand independently the pressures in each section and preferably also thepressure in each' sub-section independently of the pressure in the othersubsections. v

To carry out the aforesaid improved process I provide the table on itsunder side with a plurality of transverse partitions I1 dividing eachconcentrating section in subsections and connected to correspondingpartitions carried by the casing 4 by means of exible joints I8, therebydefining a plurality of air boxes I6 each of which is provided withthrottling means I9 consisting, in the embodiment illustrated, in twosuperposed perforated iron sheets, one of which is stationary and theother movable (Fig. 4).

These various shutters I9 enable to vary at will the quantity of airwhich enters each air box I6 defined by two adjacent partitions II thecorresponding shutter I9 and the bottom of the corresponding sub-sectionof the table; each box I6 forms thus a kind of air expanding chamberwhere the air pressure can be adjusted separately and independently; thevarious air boxes I6 of one and the same concentrating section arepreferably fed from a common air chamber 40a, 0b. 40e, the inlet of eachof which is provided also with its own throttling means Ma, IIIb, 4Ic.

It is preferred to branch in parallel the three chambers 40a, 4Gb, 40Con the same air supply pipe 42 connected to a fan (not shown). Obviouslyeach air chamber 40a, 40h, 40e could be fed by a separate air supplypipe or fan. Y

In the embodiment just described each chamber. It will thus be readilyunderstood that it is possible to adjust independently the pressure pre-'vailing in eacli'of said chambers 40a, 40h, 40e common to the variousair boxes I6 `of one and the same concentrating section of the tableand, moreover, thepressure prevailing in each of said air boxes.

This adjustment is preferably attended to in such a manner that thepressure in the air chambers'40b, is'less than in the chamber 40a butgreater than in the chamber 40o, while the pressures in the various airboxes of each concentrating section increase in accordance with thedirection of travel of the material.

I consider convenient to provide sub-partitions 43 in each air box I6with a view to thoroughly guide the flo-w air and avoid eddies.

Owing to such an arrangement the air pressure at each point of thematerial 'bed can be accurately adjusted to suit the state of the bed atthis point and this results in a marked increase lof the output of theapparatus per unit of table surface.

What I claim is:

l. In la pneumatic separator for raw material such as raw coal and thelike of the type comprising a shaking table, a shaking table ofsubstantially the same width on at least the major part of its lengthand provided locally with a plurality of channels distributed on itswhole width, open at their upper part and extending and taperingsubstantially lengthwise of the table, the height of said channels beingless than the thickness of the material bed, the table being furtherprovided aft said channels with a plurality'of transversely alignedslots each of which is in lengthwise register with a correspondingchannel, longitudinal prong like portions of the table separating twoconsecutive slots, and means for simultaneously controlling the width ofall said slots, said means including a rotatably supported cylindricalshaft located underneath said slots and extended upon the whole width ofthe table in register with the slots, further so arranged that itslateral surface will engage simultaneouslyboth transverse edges ofallthe slots and provided with a cut out portion of a length substantiallyequal to the total length of the transverse slots.

2. In a pneumatic separator for raw material, such as raw coal and thelike, of the type comprising at least one shaking table, a shaking tableprovided locally lwith a plurality of channels distributed on its wholewidth, open at their upper part, and extending and taperingsubstantially lengthwise of the table, the height of said channels beingless than the thickness of the material bed, the table being furtherprovided after said channels with a plurality of transverselyv alignedopenings, each of which is in lengthwise register with a correspondingchannel, at least one slot" pierced in the table, a rotatably supportedcylindrical shaft, located, underneath said slot, andrextended u 'ponthe whole width of the table, provided with a cut out portion, andfurther SO arranged as to dene said openings with one of the edges ofsaid portion and one edge of said slot. l

FLICIEN JOSEPH MEUNIER.

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